Solenoid operated irrigation valves are well known. The valve itself may have any suitable design and typically contains a valve element, such as a resilient diaphragm, that seals against a valve seat. Water is prevented from flowing between the inlet and outlet of the valve whenever the valve element engages the seat. When the valve element is lifted off the seat, water flow through the valve occurs, allowing any sprinklers connected to the valve to operate.
An electrical solenoid is often used to control the opening and the closing of the valve element. In some cases, the armature or plunger of the solenoid is mechanically connected to the valve element to directly lift the valve element off the seat whenever the solenoid is actuated. However, the solenoid is more typically used in a pilot valve fashion to bleed off fluid pressure from one side of the valve element when the solenoid is actuated. This decrease in fluid pressure allows the valve element to lift off its seat. U.S. Pat. Nos. 4,105,186 to Eby and 4,505,450 to Saarem et al show valves of the latter type where the solenoid is used as a pilot valve.
In either case, each solenoid operated valve in an irrigation system is connected to an irrigation controller that actuates the solenoids at predetermined times for predetermined intervals, thus allowing the sprinklers to operate in accordance with whatever program is active in the controller. A controller line, i.e. the "hot wire", extends between the controller and each solenoid for selectively carrying electrical power to that particular solenoid to actuate it. A common line, i.e. the "ground wire", is also connected to each solenoid for completing the electrical circuit to the solenoid. While an individual common line could be run between each solenoid and ground, typically only one solenoid will be grounded with that common line merely being extended from one solenoid to the next, thus decreasing the amount of wiring needed to form the common line.
Those solenoids previously used in irrigation valves have been manufactured and shipped to the field with "pig tails", i.e. two short lengths of wire protruding from the solenoid and connected internally to the solenoid's electrical structure. It is necessary to splice the pig tails into the controller and common lines when the valve is installed in an irrigation system. This is usually done by first stripping the ends of the pig tails and the controller and common lines and by then joining the appropriate lines together using electrical tape, wire nuts or the like. If the common line is extended from this solenoid, then the extension wire also has to be spliced into the common line, usually at the wire nut connection between the common line and the appropriate pig tail.
While the above noted solenoid structure and method of making electrical connections is effective, it has a number of disadvantages. First, the installer has to strip and overlay the appropriate wires and then secure them together with a wire nut or similar device. This can be time-consuming and laborious especially when working in the enclosed space of a valve box in which the valve is normally contained. Moreover, it is somewhat costly to manufacture a solenoid having "pig tails" and it is necessary to protect the pig tails from damage during shipping. Finally, solenoid operated irrigation valves are by their very nature located in outdoor environments where moisture is present. While some protection is afforded by enclosing the valve inside a valve box, nonetheless moisture will find its way into the valve box. The wire nut connections typically used are subject to degradation and/or shorting from this moisture.